Maybe I'm getting old. It used to be that shooting video included staring down the barrel of a viewfinder. Though in black and white, picture was clear, and void of stray light. Today, most video is shot with the shooter looking at an LCD screen, often a foot or more away from their face and without protection from ambient light sources. As a result, capturing clear video that's in focus has become more difficult. Fortunately, many cameras now come with focus assist built in. For long-time videographers, focus assist is a nice, but unnecessary feature. For others, it's a necessity.
Focus assist generally comes in two forms. The first is essentially a digital zoom. You see this most frequently on DSLR cameras and interchangeable lens cinema cameras where the user is expected to occasionally use prime lenses (ie. lenses that can't zoom). The typical strategy for focusing video has always been to zoom in on your subject, focus, then zoom out to your intended framing. Obviously no optical zoom makes this impossible. To get around the lens limitation, users press the focus assist button (often represented by a magnifying glass icon), to magnify the image by a factor of five or more. From there, getting accurate focus is easy. Just don't forget to reset the magnification afterwords.
The second form of focus assist is algorithm based. It analyzes the image and highlights areas of very high contrast with a sharp proximity. For example, if part of your image contains adjacent black and white elements, if the size of the transition between the black and white portions are only a couple of pixels, the focus assist will highlight that transition as an indicator of sharp focus. If the transition happens over dozens of pixels, it will be ignored to indicate soft focus. (SmallHD explains this nicely on their YouTube channel). The highlighted edges look strange on a monitor or viewfinder, as they are often very obnoxious colors (like bright green), but they are impossible to miss and easily tell the shooter what's in focus. This type of focus assist is often built into newer camcorders, but is also in many external monitors and EVFs meant to be paired with camcorders with insufficient or no focus assist built in.
The more I shoot, the more I tend to rely on focus assist. Going from a setup with sophisticated focus assist on the job to no focus assist for home movies is a difficult transition. Has using focus assist made me a better shooter or a worse one? Without a focus assist, I'll occasionally take a shot that is just off of ideal focus. When using a focus assist, that never happens. The answer to whether or not focus assist is a necessity or a crutch probably lies somewhere in between. Adapting to using a focus assist will make video shot with it better, while possibly making video shot without it slightly worse. Why worse? For me it comes down to not taking the time to set up shots that I used to.
What do you think? Do you use focus assist? If so, has your video improved as a result? Do you feel crippled without it? Leave a comment below and tell us how you focus.
Mike Wilhelm is Videomaker's Content Director.